“I’m very happy that the loan worked out.

“I promise that I will give everything for the team to be successful and I’m really looking forward to playing in front of the Yellow Wall of fans,” Maatsen said in a statement.

A Netherlands youth international, the 21-year-old moved to Chelsea in 2018 and has made 16 first-team appearances.

Maatsen impressed on loan at Burnley last season, scoring four times and laying on six assists in 42 appearances as he helped the side win promotion to the Premier League. 

Dortmund have been looking for additional cover in defence, with wing-backs Ramy Bensebaini on Africa Cup duty and Julian Ryerson injured.

“He is a player who has a lot of speed, has a strong left foot and can be used in various positions,” said Dortmund sporting director Sebastien Kehl.

Runners-up on goal difference last season, Dortmund are currently fifth on the table and sit six points away from automatic Champions League qualification.

Dortmund restart their season after the winter break away against last-placed Darmstadt on Saturday.

AFP